Advanced Agriculture: Our Farmers Use Techniques that Boost Yield and Improve the Soil

By Dr. Pat Gruber PhD, CEO of Gevo, Inc.

The creation of renewable next-generation fuel begins in America’s Heartland, where No. 2 yellow dent corn is raised in vast quantities by farmers who have been stewards of the land for generations. These farmers know their plots, and they understand how to get more corn out of each acre. Their land is their future, and the same land is often their children’s future. Farmers care about their land. It’s that simple.

When people think of corn, they think of the kind that’s on a cob at a barbecue, or in a can, or frozen in a bag, or popcorn, or for corn flakes. The vast majority of corn grown can’t be used for any of those purposes. In fact, only about one to two percent of corn grown is sweet corn, popcorn, or used for corn flakes. The other 98 to 99 percent of corn is field corn, primarily in demand for its protein content and nutritional value for animals. About 30 percent of each bushel of corn is protein, with the rest being carbohydrate.

Growing corn captures carbon from the atmosphere.

Animals use the corn protein to meet their nutritional need. By processing the corn, separating the protein from the carbohydrate, more effective feed products are produced. We’ve all read about the burping and flatulence of cows. Cows’ stomachs aren’t intended to take in simple sugars and starch. So by removing the starch, it makes for less tummy upset, and lower emissions from the cow, that is, less burping! Also by making a feed product, the nutritional value is packed into a smaller volume, making it more practical, and less expensive to ship.

So then, what to do with the carbohydrate? It doesn’t have nutritional value, but if the carbohydrate is used for something else, so it has value on its own, it lowers the cost to produce the protein. Should we use the carbohydrate to produce more high-fructose corn syrup? More corn sweeteners? It seems to me, we as a society already are taking in too much sugar, given our rates of diabetes and obesity. We think using the carbohydrate to make advanced biofuels that help to solve a problem for all of us makes sense. It isn’t a compromise of food versus fuel. Instead it’s about producing fuels, leveraging the vast potential of agriculture, while producing better nutrition for the food chain, without compromising the environment. 

The nutritional value of corn is captured in the protein and nutrients that are fed to animals. The animals that eat this corn are living machines that convert the protein in each kernel into meat for human consumption.Those animals play a critical role in the circular economy as well, both economically and nutritionally. For example, farmers utilize livestock manure for fertilizers and biogas while the meat provides protein into the food chain.

In any quick Google search regarding growing of corn, a person will see that corn take lots of nutrients like nitrogen, in particular, but also phosporous and potassium. There is lots of discussion about the high levels needed to grow corn in high yield, as well as issues around ground water runoff and such. So where do these nutrients go? They mostly end up in the corn kernels, stalks, leaves, and roots. In the Midwest farmers have figured out that if they leave the root systems intact, and leave the stalks and leaves on the field after harvest, a good portion of the nutrients stay on the field, and can be used next year to grow corn. They also have learned that by using manure as a fertilizer, nitrogen and phosphorus can be recycled to the field, reducing the amount that needs to be added the next year. Of course no farmer wants to waste nutrients that go on to the field, so many have adopted precision agriculture where, using GPS and precise field measurements, farmers only apply the necessary nutrients, when and where they are needed. By doing so they improve their yields, while minimizing cost of chemicals. In Minnesota, all of the farms have ground water protection, so runoff issues are reduced.

By using low-till and no-till farming, the farmer preserves the root structure from the corn from previous years, planting precisely between the rows. This keeps the precious soil in place, so it can’t blow away, as those root systems help to keep it in place while they sequester carbon in the soil.

In agriculture, science and technology are crucial to improving the yield of each acre of farmland. Farmers use satellite imagery to target problem areas in fields where the effects of insects, or drainage problems, or other factors have a negative impact. They program their tractors and harvesters with GPS-controlled precision to mitigate these adverse effects.

Farmers have a deep understanding of the fields they work, and they know the health of their soil is their key resource to make each year a success. Here are the facts:

  • Soil is made up of a combination of mineral and organic matter, and farmers don’t just take away from the fields, they actively regenerate soil to keep producing year after year.
  • Low-till or no-till methods, sometimes also called strip-tilling or zone-tilling, only use a four-inch-wide (10-cm-wide) strip of soil—less than the width of a standard sheet of paper. Farmers plant the seeds in rows, and fertilize directly in the strip where it can do the most good.
  • Zone-tilling helps keep the soil in place, which allows more carbon to stay there, where it belongs.
  • Farmers till these strips between the rows of last year’s corn, leaving the root structure of the previous year’s crop to decay and become that organic matter in the soil, creating a healthy environment for the new crop.
  • The nutrients still contained in the root and stalk of the corn left in the field after harvest spread through the soil and stay there, building that healthy soil that will help next year’s plants grow better and need less fertilizer to do it.

Best of all, organic matter that goes into the dirt is carbon that is sequestered in the soil. As Gevo makes renewable fuels, it captures anywhere from 0.8 to 4 kilograms of carbon dioxide in the soil for every gallon of renewable fuel produced.

Minimal tilling between the rows keeps carbon in the soil, and improves the soil each year.

Increasing carbon in the soil offsets fossil fuels, but even more than that, it also increases feed and food production for a growing global population on the same acre of land. Meaning the increasing demand for food requires less area because the land our farmers use is being used to its fullest potential. The use of this natural storehouse could allow us to sequester an additional 1 billion to 3 billion tons of carbon annually. That’s equivalent to roughly 3.5 billion to 11 billion tons of carbon dioxide emissions. Most of the biomass used to produce Gevo biofuels comes from resources that use farming techniques that build soil organic carbon.

As we mentioned earlier, renewable fuel production at Gevo does not require the entire kernel of inedible corn to produce fuels. The process uses the starch, and that leaves plenty of protein from the corn to be forwarded into the food systems. The protein the company captures—and there is a lot of it—is turned into animal feed, to the tune of about 10 pounds (around 5 kilograms) per gallon of isobutanol produced. On a tonnage basis, Gevo produces more animal feed than biofuels at the Luverne, Minnesota, production plant.

Because high-protein animal feed creates an additional revenue stream for the company, it helps to offset the cost of producing advanced renewable fuels like isobutanol. This feed is considered to be better for livestock and some studies have shown results in healthier livestock that produce better meat for human consumption. Gevo’s overarching goal of reducing GHG emissions means there are additional benefits to this animal feed. First, Gevo sells its animal feed to farmers in the area around the facility, so the feed is not transported over long distances. Secondly, high-protein animal feed helps reduce methane emissions from livestock. Methane is a greenhouse gas that is widely understood to retain atmospheric heat more effectively than carbon dioxide.

Farmers who keep livestock as a complement to growing corn have a natural source of inexpensive fertilizer from manure that preserves the nutrients from the corn on the farm, without trucking in synthetic fertilizers. Manure can be placed in digesters that use natural yeast organisms to break down the manure, releasing methane, which can then be captured and used for energy as renewable natural gas—called biogas. Gevo is planning to install these digesters at area farms and use the biogas to offset even more of the energy use at the plant with this renewable resource. The nutrients from the manure that was put into the digesters then go back onto the farmer’s land to help them increase yields without the need for synthetic fertilizers. This not only helps the fields where this organic fertilizer is applied, but it also works to keep synthetic fertilizers out of the water systems, which can be harmful downstream if synthetic fertilizers run off with heavy rains.

Gevo is on a crusade to help battle the problems seen in conventional fuel production as well as the problems in food/ agricultural systems. Only by daring to address these problems together will any solution be genuinely sustainable.